Means of withholding braking action when an hydraulic brake is released



June 2, 1953 w. F. SANDERS 2,640,563

momma MEANS OF WIT BRAKING ACTION WHEN AN HYDRAULIC BRAKE IS RELEASED Filed March 4, 1949 2 Sheets-Sheet l 56 INVENTOR H5 .2. M/fer lf janaens 4 W ATTORNEY June 2, 1953 w, SANDERS 2,640,563

MEANS OF .WITHHOLDING BRAKING ACTION WHEN AN HYDRAULIC BRAKE IS RELEASED 2 Sheets-Sheet 2 Filed March 4, 1949 INVENTOR Wa/zer r 5anc/er5 BY w % ATTORNEY Patented June 2, .1953

WITHHOLDING .AC- HON aiN .HYDBAUIZID REIJEKSED invention relates to hydraulic 'ibrakes of the'fh/pe which restrain the rotation of 'a'f otating body lbythe throttling action of a eontrolledvalve on ilihe flu d circulated by the motion of the pistons, :and especially the pistons ;of the brake for which I, jointly with Clifton C. Stevens, have applied Zior a patent of the limited States, :under SeliaJlNo. 7311:2144, :filed on'Eebruary 2.4 fliieignow issued as PatentNo. a 55 18 ;9.1' 9;and more especial- 1y to means for holding the pistons thereof :in withdrawn 'positions when the brake 'has been released.

The object of my invention is to provide an automatic means which prevent "the pistons from Jfiollowing the retreating movement of the brake cams, thereby releasing the unnecessary Dumping action of said istons onthe 'fiuid controlling said brakes.

.1 a tain this and .other objects as will be perceived hy those familiar with the art, "by the videviees, .mechanisms and arrangements illustrated in the accompanying ,d-rawmgs, -which .1 is an end elevation, partly "in section, of the braking mechanism of my improved hydraulic brake; Fig. .2 is a cross-section thereof; Fig. 3 is .a section thereof showing 'my releasedbrake holder; .Fig. ,4 is an elevation of the springholdlng washer; .Fig. .5 is a plan showing my :im provedlhydranlic brake, as applied to the rear wheels ofia truck; and Fig. '6 is a-viewiillustrating themeans of operating the released-brakeholding mechanism. Identical numerals of reference refer to the .same parts throughout the several views.

Referring to the drawings, :it will be seen that, briefly, the ihrake to which my invention is 310;- pIied, compr'isesa pair of eccentric circular cams 1.0 and .11, secured to the rotating axle .12 "which rotates within the fixedhousing '1 ii, having a plurailitypr cylinders 1 .1 in which two series of pistons f5 and T6 reciprocate, the pistons l 5 being in contact with the cam "It, and the pistons "Hi heing in contact with thelcam LL, all said pistons being urged toward the axle 12 'by means of the compression springs ll mounted between them and the heads of the respective cylinders :M. .a suitable fluid fills "the cylinders and the passages connected thereto. The cams successively force the pistons outward in the cylinders, against the actioniof the springs 11, thus forcing the ffinid out of the respective cylinders into the hlgh pressure passages 1'8 in the housing 1'3.

A manifold comprising a, circular ring [9, of rectangular section, is tightly secured to the flat face of the housing l3. The contacting surface of the ring 1-!) is provided three concentric grooves 20, 2| and 22 each of a manifoild *for a different set of similar passagesin the I3 and opening into the "respective manifoldgrooves. "The highpressure passages W8 carryit-he fluid, pressed out of the cylinders by the action of the cams 10 'or H on the pistons i i or 'I 6,;1 astsuita'hle check valves not esl-iowm) land into-the manifold passage 24] --and thence 'by'the high pressure :pipes M to the receiving :sidegif the valve 2 6, which is 'thus common to an the whee-1 brakes. This passes through the valve '16,, substantially without resistance ii the said valve 26 is'fully open, but with'resistanceif fit partial 1y or wholly closed, andleaves "the said valve by the low pressure pipes 26 to return to the cylinder 14 through the manifold passage *22, and suitable check-"valves (not shown) and soto the low pressure passages23, thus'flll ing ltlp thespace evacuated hy the high pressure fluid. 'ilhe fluid always travelsin the same direction in said passages and pipes and completely fills them and circulates constantly, passing through the valve 26 with more 'or less resistance .accordirig as the driver applies a force to the brake lever 21.

This connection between-the lever 21 and the brake "valve 2-6 may be of any of the wellaknewn means sech as by means of electrical connection,

as by the lever *2 controlling a *rheostat' '11) i which controls the current in the electrical; wires M which, in turn, controls by suitable t wel'le kno-wn means, :such as .-a solenoid '12, the position of the valve 26 in relation to the how of fluid'therepast. Thus, as the pedal 21 is depressed to applythe brakes, {the valve 2'6 is moved to resist the tree passage 'of fluid therethrough and thuss a Elana/king force is applied to the pistons 1-5 and 16.

said highpressure passages Niall epen into the manifold groove '20 having suitable check valves therein. Similarly, as the pistons are urgediinward :by the springs I 1, the fluid' is drawn into the "respective cylinders 44 the housing from the low pressure passages all ropenihg into the iowpressuremanifold groove :22 .andmast suitable check valves-in the passages 23 :receivmg the .fluid therefrom. The said manifold 2,0 and 2-2 in "the -fixed-ring F8 communicate mespectively 'with the pipes 2 4 and leading (to the two sides of the control valve '26, mom-rted on the chassis and controlling the resistance of proved manner, not shown. It is evident that when the valve 26 is fully open there is substantially no resistance to the motion of the pistons 15 in the cylinders l4 under the outward impulse of the cams l and the inward pressure of the springs l1, however it is plain that such motion is unnecessary and wasteful, and my present invention is for ther urpose of eliminating all such motion after the brakes are released by the driver. This is accomplished by holding the pistons It: at their outermost positions when the brake mechanism is released.

The heat developed in the brakes heats :the fluid in the system. I therefore pass the high pressure pipe 24 through a water cooler 62, and

released by the driver, all the plugs 38 on all the brakes are simultaneously forced against the respective brake pistons, so that as the cams ID or I! force the pistons outward, they are held in that extreme outward position against following the inward movement of the cams under the action of the springs H by the faces 39 of the plugs 38 engaging-the said pistons or. 16, thereby freeing the wheels from any resistance to rotation by said brakes.

Having described my invention, what I claim and desire to secure by Letters Patent, is:

l 1. A means of withholding braking action when an'hydraulic brake is released, comprising, in

the low pressure pipe through a similar water cooler 65. A circulation pipe fifijoins the coolers 62 and B5. A water storage tank '6'! is connected to the cooler 62 by a pipe 68, and to the coolerv 65 by a pipe 69. The heat-developed is therefore largely absorbed by the cooling water in the above cooling system.

In Fig. 6 is illustrated a portion of the brake controlling foot-lever 21 in its depressed, or brake-applying position operating against the tension of the spring 28. The lever 2'! has an extension 29. A cylinder is mounted adjacent to the extension 29and contains a plunger 3!, having a rod 32 passing out of the cylinder 39 and through a flexible cap 33 to an adjustable head, 34. 'Ifhe plunger 3i is adapted to be pushed inthe cylinder against the action of a compression spring 3 5, lby the extension 29, under the actionof the spring 28 when the foot-lever is released to release the brake, p a

The cylinder 30 is provided with an outlet pipe 36 which leads therefrom to the manifold ring it, above described, where it communicates with the central maniiold groove 2 l.

Referring, now, to Figs. 2 and 3 it will be seen that the housing I3 has a series of passages 31, each of which communicates with the manifold groove 2|, and each extends through the housing l3; into the brake cylinders M at a point in line with the piston 15 when the piston is in its furthest outward position.

;A,l? ll Or plunger 38 is mounted in said passage 3 l and is provided with a suitable outer section 3 9, of I rubber or other suitable material, which is adapted to engage the piston 15 and to press thereagainst to resist the motion of the piston under the action of the spring 17. Thecylinder 30, pipe 36, manifold groove 2! and all the passages 31 are filled with a suitable fluid, so that when the foot-lever 2? is released, to release the brake, and the piston 3l forced outward, as above described, the fluidtherein will force the plug 38 against the, piston 15, to hold it in its withdrawn positionafter the cam I!) has forced it thereinto, thus removingit from-engagement with the cam, except momentarily, andeliminating all resistance to the rotation of the cams from the brake. Springs 40 are secured to the plugs 38 and to a bar 4 l mounted on a washer 42 fastened between the housing I3 and the ring [9 at each such passage 37. I A; chamber 43 is mounted in communication with the cylinder 30, through the passage 44. Said chamber 43 is kept full of the fluid being used, by a supply pipe 45 leading thereto from a reserve tank (not shown).

Thus it will be seen that, when the brake is combination with an hydraulic brake adapted to be applied to a rotating body and having a plurality of reciprocating floating pistons mounted in braking cylinders in a fixed housing and actuated. by said rotating body against the action of springs, and actuating a flow of fluid, and means to throttle said flow of fluid to resist the motion of the pistons whereby to apply braking action to the rotating body, means in said housing releasably and frictionally engaging said pistons in said cylinders, and means connected to said throttling means adapted to actuate said piston-engaging means, whereby said pistons may be held frictionally at the extreme outer ends of their travel against the action of the springs when said throttling means is released.

' 2. A mechanism as set forth in claim 1, wherein each said means in said housing and engaging one of said pistons, comprises an hydraulic hold ing cylinder having a free plug therein adapted to engage said piston whereby, on an increase of the hydraulic pressure in said holding cylinder, said plug is applied frictionally to said piston to prevent its inward motion under the action of one of said springs.

3. A mechanism as set forth in claim 1 wherein said fixed housing has inflow and outflow passages for each braking cylinder, together with a fiat ring secured to the face of the'h'ousing and having three concentric manifold grooves therein, two of said grooves communicating respectively with all of said inflow and outflow passages and with said throttling means whereby all of the braking pistons are equally and simultaneously resisted when the flow of fluid is throttled, and wherein a holding cylinder is associated with each braking cylinder, together with a plug in each holding cylinder for frictionally engaging the piston, a passage from each holding cylinder communicating with the third manifold groove, and wherein said means connected to the throttling means comprises a hydraulic cylinder with a plunger adapted to be engaged and moved by the throttle actuating means when the latter is released, whereby all of said plugs maybe brought into frictional engagement with said brakingpistons to hold the latter in disengaged positions against the action of said springs.

WALTER SANDERS.

"Rash etal Aug. 22, 1933 

